Surface and Biological Activity of Some Prepared Iminium Surfactants Based on Schiff Bases

A series of novel iminium surfactants were prepared through quaternization of different prepared fatty Schiff bases with benzyl chloride. The chemical structures were confirmed using FTIR, ¹H-NMR and mass spectroscopy. The surface properties and biological activity of these surfactants were investigated. The surface parameters including critical micelle concentration (CMC), maximum surface excess (Γ_max) and minimum surface area (A _min), Efficiency (PC₂₀) and Effectiveness (π_CMC) as well as the free energy of micellization ( $ \Updelta G_{\text{mic}}^{\text{o}} $ ) and adsorption ( $ \Updelta G_{\text{ads}}^{\text{o}} $ ) were calculated. It was found that the prepared compounds have good surface and biological activity.     

The Effects of Amide Bonds and Aromatic Rings on the Surface Properties and Antimicrobial Activity of Cationic Surfactants

The cationic surfactants containing aromatic rings and amide bonds, N,N-dimethyl-N-dodecyl-2-pyrimidinylcarbamoylmethyl ammonium chloride ( a ), N,N-dimethyl-N-dodecyl-2-thiazolylcarbamoylmethyl ammonium chloride ( b ), and N,N-dimethyl-N-dodecyl-phenylcarbamoylmethyl ammonium chloride ( c ), were synthesized and characterized. The surface tension and conductivity values were employed to investigate the absorption and micellization behavior of the three cationic surfactants. The results showed that the synthesized surfactants have shown a low critical micelle concentration (CMC) and a high adsorption efficiency (pC₂₀) compared with the traditional cationic surfactant of N,N-dimethyl-N-dodecyl-N-benzyl ammonium chloride ( BAC-12 ). The aromatic rings of the a , b , and c molecular structures were analyzed using the ¹H NMR spectra for electrostatic repulsion effects between hydrophilic headgroups. The size distribution of the micelles was derived using dynamic light scattering (DLS) techniques. In addition, the foaming ability of a , b , c , and BAC-12 was investigated and the antimicrobial activity of a , b , c , and BAC-12 against Escherichia coli, Staphylococcus aureus, and Bacillus subtilis was examined. The effects of amide bonds and aromatic rings on the surface properties and antimicrobial activity of a , b , and c were analyzed and compared with BAC-12 of the same alkyl chain length. The synthesized surfactants exhibited a high surface ability and better antibacterial activity compared with BAC-12 .     

Surface Parameters and Biological Activity of <Emphasis Type="Italic">N</Emphasis>-(3-(Dimethyl Benzyl Ammonio) Propyl) Alkanamide Chloride Cationic Surfactants

Three cationic surfactants containing amide groups were prepared by quaternization of dimethylaminopropylamine with benzyl chloride. FTIR and ¹H-NMR spectroscopy were used to confirm the chemical structure of the prepared cationic surfactants. The surface parameters were estimated using surface tension measurements at three different temperatures. The prepared cationic surfactant showed a lower CMC than conventional cationic surfactants. Thermodynamic parameters of adsorption and micellization depend mainly of alkyl chain length and temperature. The adsorption process is more favorable than micellization. The biological activity of the three surfactants was estimated using inhibition zone showing that amidoamine cationic surfactants have good activity and the surfactants C12Bn is the most effective one.     

Synthesis,Surface-Active Properties,and Emulsification Efficiency of Trimeric-Type Nonionic Surfactants Derived From Tris(2-aminoethyl)amine

Trimeric-type nonionic surfactants based on tris(2-aminoethyl)amine were prepared. N-alkyl chloride (namely, octanoyl chloride, n-decanoyl chloride, n-dodecanoyl chloride) was reacted with tris(2-aminoethyl)amine in the presence of toluene and triethylamine. The products were partially reduced and then ethoxylated by poly(ethylene glycol) of molecular weights 400, 1,000, and 2,000 g mol⁻¹. The structures were confirmed by infrared (IR) and ¹HNMR spectroscopy. The molecular weights of the surfactants were measured by gel permeation chromatography (GPC). The properties of the prepared compounds were investigated by the surface tension, interfacial tension, and cloud point. The emulsification power of the prepared surfactants for oil-in-water emulsions was also studied and the emulsion stability was monitored by an optical microscope and the bottle testing method. Some factors affecting the emulsion stability were investigated     

Retracted: Synthesis,Characterization, and Surface Activities of Polymeric Cationic Thiol Surfactants in Aqueous Medium

A series of cationic polyurethane surfactants [PQ_8-18] were synthesized by the reaction of alkyl bromoacetate (namely: octyl-, decyl-, dodecyl-, tetradecyl-, hexadecyl-, and octadecyl bromoacetate) as quaternizing agents and modified polyurethane contains tertiary amine species. Modified polyurethane was prepared by the reaction of toluene diisocyanate (TDI) and triethanol amine monomercaptoacetate. The chemical structures of the prepared surfactants were confirmed using elemental analysis, Fourier transform infrared spectroscopy (FTIR), and Proton nuclear magnetic resonance (¹H NMR) spectroscopy. The molecular weight measurements of the prepared polymers showed that the segments of each polymer contain average 10 units of the urethane-triethanol amine mercaptoacetate. The surface activities of the prepared surfactants including: surface tension (γ), effectiveness ( π_cmc), concentration at micelle formation (CMC), efficiency (Pc₂₀), maximum concentration at the interface (Γ_max), and the average area occupied by each surfactant molecule at the interface at equilibrium ( A _min) of surfactants solutions were established at 25°C. The surface tension and the critical micelle concentration values of the prepared surfactants were gradually decreased by the gradual increase of their alkyl chain length. The prepared cationic surfactants showed efficient activity as inhibitors for dissolution of carbon steel in an acidic medium and also as a biocide against the growth of bacteria, fungi, and yeast.     

Nonionic Isatin Surfactants: Synthesis,Quantum Chemical Calculations,ADMET and Their Antimicrobial Activities

The most challenge task in the building up of surface-active molecules is maximizing their surface activity with good biological activity. A nonionic surfactant (N-isatin-EO _m-C _n where m is 5, 7 and 9 ethylene glycol units and n is 8, 10 and 12) is achieved by first reacting isatin with chloroacetic acid and then with different types of ethoxylated (C₈–C₁₂) fatty alcohols that possess 5, 7 and 9 ethylene oxide units. The prepared surfactants were characterized by FTIR and ¹H NMR to confirm the structure. The surface activity, biodegradability, antimicrobial, and antifungal activity of the surfactants were evaluated. In addition, quantum chemical calculations and computations of oral bioavailability were performed. The obtained data show that all the synthesized compounds had good surface activity, biodegradability and biological activity.     

Synthesis and Characterization of Cationic Surfactants Based on N‐Hexamethylenetetramine as Active Microfouling Agents

Four cationic surfactants of quaternary hexammonium silane chloride based on hexamethylenetetramine and alkyl chloride were synthesized. The chemical structures of the prepared cationic surfactants were elucidated using Fourier transform infrared (FT‐IR) spectroscopy and mass spectrometry analysis. The surface and thermodynamic properties of the prepared surfactants were also studied. The performance of these cationic surfactants as microfouling agents against two strains of Gram‐negative bacteria, namely, Pseudomonas aeruginosa and Escherichia coli, and two strains of Gram‐positive bacteria, namely, Staphylococcus aureus and Bacillus subtilis, were evaluated as antimicrobial agents. The results showed that the maximum antimicrobial activity was detected for N‐hexamethylenetetramine‐N‐ethyl silane ammonium trichloride (Ah). The maximum and minimum antimicrobial activities were 73 and 60 % against S. aureus and E. coli, respectively, at a concentration of 5 mg/l, pH 7, and 37 °C.     

Synthesis and Properties of Di‐Chain Esterquat Surfactants

A series of cationic surfactants, di‐chain esterquat surfactants (EQs), were synthesized from N‐methyl diethanolamine, hydrochloric acid, ethylene oxide, and caprylic acid, decylic acid, or lauric acid by a three‐step process. The synthesized surfactants were characterized by IR, MS, and ¹HNMR. Surface properties, antibacterial activity, and biodegradability of the synthesized surfactants were investigated. The results showed that synthesized EQs exhibit high surface activities and good biodegradability. Further, the synthesized surfactant, N,N‐di‐[O‐decanoyl‐2‐hydroxyethyl]‐N‐hydroxyethyl‐N‐methylammonium chloride, exhibits excellent antibacterial activity against E. coli and S. aureus.     

Synthesis of Bis[<Emphasis Type="Italic">N</Emphasis>,<Emphasis Type="Italic">N</Emphasis>′-(alkylamideethyl)ethyl] Triethylenediamine Bromide Surfactants and Their Oilfield Application Investigation

Bis[N,N′-(alkylamideethyl)ethyl] triethylenediamine surfactants are quaternary ammonium salt Gemini surfactants with amide, which are synthesized from fatty acid (dodecanoic, hexadecanoic, tetradecanoic and octadecanoic) methyl esters, triethylene tetramine and ethyl bromide. The chemical structures of the prepared compounds were characterized by elemental analysis, FTIR and ¹H-NMR spectra, melting point and Krafft point. Several properties of the synthesized surfactants were studied including surface tension, critical micelle concentration, interfacial tension, emulsification power, salt effect, corrosion inhibition efficiency and biological activity. The results show that the surface activity, critical micelle concentration and interfacial activity are correlated to their chemical structures. The emulsification power measurements of these surfactants show their low emulsifying tendency towards Tazhong’s crude oil from Tarim Oilfield. The synthesized surfactants also exhibit high biocidal activity towards Gram-positive and Gram-negative bacteria and fungi. This activity increases with the increase of alkyl chain length. The corrosion measurement of these surfactants in acidic media with a weight loss technique show good protection of mild steel alloys against acidic environments. These properties suggest that the synthesized compounds have potential for application in the oilfield area.     

Biological Behaviors of Guanidine-Based Cationic Surfactants

The biological properties of novel guanidine‐based cationic surfactant including mono‐alkylguanidine (CnG), N,N,N′‐dimethyl alkylguanidine (CnMG), dicephalic guanidine surfactant (CnGQ), heterogemini guanidine surfactant (diCnGQ) were investigated. Antimicrobial activity was determined via the inhibition of cell viability of the prepared compounds, which was measured against three strains of a representative group of microorganisms. The inhibitions of cell viability were basically about 90 % at the concentration of 25 mg L^?1 to alkyl guanidium salts (CnG, CnMG), and higher than 95 % at a concentration of 10 mg L^?1 to dicephalic guanidine surfactants (CnGQ) and heterogemini guanidine surfactants (diCnGQ). The interactions of bovine serum albumin (BSA) with guanidine surfactants were investigated by fluorescence technology and the effect on BSA conformation follow the order: diC12GQ > C12GQ > C12G > C12MG. At any particular concentration, the biological activity depends on the alkyl chain length to any series of guanidine‐based cationic surfactants.     

Synthesis and Surface Properties of Polyether-Based Silicone Surfactants with Different Siloxane Groups

A series of polyether-based silicone surfactants with different hydrophobic chains (trimethylsiloxy, triethylsiloxy, and triisopropylsiloxy) were synthesized. The molecular structures were confirmed using ¹H nuclear magnetic resonance (NMR), ¹³C NMR, ²⁹Si NMR, and fourier transform infrared spectroscopy (FT-IR). The effect of the siloxane groups on the physicochemical properties, surface tension (γ), critical micelle concentration (CMC), surface tension at the CMC (γ_CMC ), adsorption efficiency (pC₂₀), surface pressure at the CMC (π_CMC ), maximum surface excess (Γ_max ), single silicone surfactant molecule at the air/water interface (A_min ), and the standard free energy of adsorption (), of the polyether-based silicone surfactants was investigated. Results indicate that the polyether-based silicone surfactants can reduce the surface tension of water to approximately 25–31 mN m⁻¹ and the surface activity of silicone surfactants is enhanced with increasing branched trimethylsiloxyl and sterically hindered siloxane groups.     

Unconventional Synthesis of Pullulan Abietates

Pullulan abietic acid esters (pullulan abietates) of different degree of substitution (DS) were synthesized homogeneously in N,N-dimethylacetamide using differently in situactivated abietic acid derivatives. In situ activation was achieved with p-toluenesulfonyl chloride, N,N‘-carbonyldiimidazole and iminium chloride formed from oxalyl chloride/N,N-dimethylformamide. The DS values of the biopolymer esters determined by acid-base titration after saponification indicated that in situ activation with p-toluenesulfonyl chloride is most efficient while in case of the in situ activation with N,N‘-carbonyldiimidazole almost no polymer degradation occured. The pullulan abietates were characterized by elemental analysis, GPC, FTIR-, ¹H- and ¹³C NMR spectroscopy.     

Synthesis and some studies on fluorinated cationic surfactants: surface and biocidal activities

Three fluorinated cationic surfactants were prepared by condensing N-(2-bromoethyl)perfluoroalkylamides with stoichiometric amounts of pyridine, triethanolamine, and triethylamine to produce three quaternary ammonium salts. The surface and biocidal properties of these surfactants were investigated to find the relation between the structure of the hydrophilic portion of the compounds and their efficiency as biocides. The properties studied included critical micelle concentration (CMC), effectiveness (II_CMC), surface excess concentration (T_max), and area occupied by a molecule (A_min). Free energies of micellization (ΔG _mic ^o) and adsorption (ΔG _ads ^o) of the surfactants in aqueous solution were calculated. The minimal inhibitory concentrations of the prepared compounds were tested against five strains as representative group of microorganisms.     

The Preparation and Kinetic Properties of Fully-Functionalized Imidazole Vesicles

The 4-imidazolecarboxylic acid ester of N,N-dihexadecyl-N-methyl-N-(β-hydroxyethyl)ammonium chloride ( 1 ) and an analogous monohexadecyldi-methylammonium ion surfactant ( 2 ) were prepared from readily available starting materials. Surfactant ( 1 ) formed fully-functionalized imidazole vesicles which are powerful catalysts for the cleavage of p-nitrophenyl acetate, p-nitrophenyl hexanoate and 4-acetoxy-3-nitrobenzenesulfonate. Maximum observed rate constants ([1] = 3.4 × 10⁻³ M, pH 8.0, 0.01 Tris buffer, μ = 0.01, 25°C) are 2.82, 16.3 and 14.3 s⁻¹, respectively, for the three substrates. These and related kinetic parameters are compared with those of imidazole-functionalized micellar surfactants, such as 2.     

Some Sugar Fatty Ester Ethoxylates as Demulsifiers for Petroleum Sludge

Several ethoxylated sugar fatty ester surfactants were prepared by the reaction of glucose with three fatty acids, namely, adipic, stearic and palmitic acids to produce GA, GS and GP esters. These glucose esters were then ethoxylated by four different molecular weight polyethylene glycols, namely, 400, 1,000, 2,000 and 4,000 mol L^?1. The prepared ethoxylated esters (12 compounds) were characterized by IR and ¹H‐NMR spectroscopy. The surface activity of the prepared compounds was thoroughly studied by measuring the surface tension of different solutions of these compounds at three temperatures, namely 298, 308 and 318 K. From the surface tension‐concentration plots of these compounds some surface properties, such as CMC (critical micelle concentration), Γ_max (maximum surface excess concentration) and A_min (area occupied per molecule) were calculated. The surface properties of the prepared surfactants were correlated to their chemical structure. It was found that the CMC decreases when increasing the molecular weight of polyethylene glycols, whereas A_min increases. Furthermore, the demulsification test was carried out and the results of demulsification efficiency were correlated to the chemical composition of the investigated compounds. Some factors that affect the demulsification efficiency were also considered. The oil phase recovered from the treated sludge was characterized and mixed with fresh crude to improve its API.     

Design and Surface/Interfacial Properties of Asymmetric Triazine Carboxyl Betaine Surfactants

The design, synthesis and interfacial behaviors of six asymmetric carboxyl betaine surfactants (BC_m?n, m, n = 8, 10, 12, or 14, m ≠ n) derived from s‐triazine, which were prepared from cyanuric chloride, aliphatic amines, N,N‐dimethylpropane‐1,3‐diamine, followed by the reaction with sodium chloroacetate, are reported. The structures were confirmed by MS, ¹H NMR and FT‐IR. Compared with symmetric surfactants (BC_n?n, n = 8, 10, 12, or 14) we previously synthesized, the asymmetric series show superior surface activity. The γ_CMC of surfactants BC_10?8, BC_12?8, BC_14?8 and BC_12?10 is all below 30 mN/m. The minimum alkane carbon number of these ten surfactants is determined to be between 10 and 14. The interfacial behaviors between the alkanes and the solutions of triazine carboxyl betaine surfactants show that surfactants with a total carbon number in hydrophobic chains between 16 and 22 exhibit the ability to reduce the interfacial tension to an ultra‐low value (10^?3 mN/m). The surfactants with longer hydrocarbon chains display strong affinity to the alkanes with longer chains.     

Novel biocidal polymers based on branched and linear poly(hydroxystyrene)

New biocidal polymers based on branched as well as linear poly(p-hydroxystyrene) were synthesized. Biocidal polymers were synthesized in two steps by creation of active centers via chloroacetylation of linear and branched poly(p-hydroxystyrene) using chloroacetyl chloride. The second step involves the immobilization of onium salts onto the chloroacetylated polymers. All the prepared polymers were characterized using elemental microanalysis, FT-IR, ¹H NMR spectra, and TGA. Antimicrobial activity of the prepared polymers was tested against various pathogenic microorganisms. The antimicrobial activity was found to be affected by the active group and the tested microorganism. The phosphonium salts showed higher activity than ammonium salts.     

Glycine Surfactants Derived from Dodecenyl Succinic Anhydride

We report the synthesis and properties of two surfactants with a novel head group based on glycine. A monocarboxylic surfactant N-glycine methyl ester (2-dodecen-1-yl succinamic acid) (I) was prepared by ring opening of an n-alkyl succinic anhydride. Hydrolysis of the ester functionality yields a dicarboxylic acid II. The sodium salts of I and II were effective surfactants at neutral pH giving a low minimum surface tension (<30 mN m⁻¹ at 20 °C). At high pH (~12) the surface activity of both surfactants is reduced compared to neutral pH, indicating that at neutral pH an ‘acid soap’ is formed. The pK _a of the acid form of the surfactants was determined. Addition of calcium ions reduced the CMC of II but did not reduce the surface tension above the CMC. The resistance of II to calcium ion precipitation was measured at pH 7.     

Synthesis,Characterization, Surface,and Thermodynamic Studies of Alkyl Tetrachloroferrates: Performance Evaluation of Their Nanostructures as Biocides

Decyl and dodecylamino tetrachloroferrates were synthesized and characterized using Fourier-transform infrared spectroscopy (FTIR), elemental analysis, X-ray diffraction (XRD), nuclear magnetic resonance (¹H-NMR), and atomic absorption spectroscopy (AAS). The surface properties of the cationic surfactants including critical micelle concentration, effectiveness, minimum surface area, and maximum surface excess were determined using surface tension measurements. The effectiveness of surface tension reduction (π_cmc) was found to increase as the hydrophobic chain length increases with values of 30 and 34 mN m⁻¹ for C₁₀ and C₁₂, respectively. Moreover, the effect of temperature on micellization was determined over the range of 35–55 °C. Thermodynamic parameters (ΔG°, ΔS°, and ΔH°) were calculated and the results indicate a spontaneous process for both micellization and adsorption. The nanoparticles (NC₁₀ and NC₁₂) of the prepared surfactants were obtained using the ball mill technique. The particle size and morphology of the nanoparticles were determined using transmission electron microscope measurements. The antibacterial study of the nanoparticle surfactants revealed their strong efficiency against fungi and different pathogenic bacteria compared with the original surfactants.     

Synthesis and Evaluation of Novel Amido-Amine Cationic Gemini Surfactants Containing Flexible and Rigid Spacers

New amido‐amine‐based cationic gemini surfactants with flexible and rigid spacers and different hydrophobic tails were synthesized and characterized. These gemini surfactants were prepared by a modified procedure through amidation of long chain carboxylic acids using 3‐(dimethylamino)‐1‐propylamine followed by treatment with halohydrocarbons. The effect of the trans and cis conformation of the spacer double bond was investigated by means of critical micelle concentration, surface tension reduction, and thermal stability. The short‐term thermal stability of the gemini surfactants was assessed using thermogravimetric analysis (TGA) and the long‐term thermal stability was examined by a unique approach based on structure characterization techniques including NMR (¹H and ¹³C) and FTIR analysis. TGA results demonstrated excellent short‐term thermal stability since no structure degradation was observed up to 200 °C. Structural characterization revealed impressive long‐term thermal stability of the gemini surfactants with no structure decomposition after exposing them to 90 °C for 10 days. The critical micelle concentration of gemini surfactants was found to be in the range of 0.77 × 10^?4–3.61 × 10^?4 mol L^?1 and corresponding surface tension (γ_CMC) ranged from 30.34 to 38.12 mN m^?1. The surfactant with the trans conformation of spacer double bond showed better surface properties compared to the surfactant with the cis conformation of spacer double bond. Similarly, increasing surfactant tail length and spacer length resulted in decreasing CMC values. Moreover, bromide counterion showed improved surface properties compared to chloride counterion.